This invention relates to a control apparatus for a hybrid vehicle which can prevent discharge of unburned combustible gas when automatically stopping a vehicle, can improve a feeling or sensation during stopping of the vehicle, and can improve start-up performance.
Some motor vehicles are of a type commonly called a hybrid vehicle having an internal combustion engine and an electric motor disposed therein as the power sources of a propulsion system. The engine mounted on the hybrid vehicle is provided to directly connect with an electrical motor having a vehicle driving function and an electrical power generating function. The hybrid vehicle has a motor control apparatus to control both driving and power-generating states of the motor based on a driving state of the hybrid vehicle and a driving state of the engine.
In a hybrid vehicle, there is a control apparatus to control so as to automatically start up and stop during driving of engine. The control apparatus of a hybrid vehicle controls to automatically stop the engine when an automatic stop condition without pressing of an accelerator pedal is satisfied. The control apparatus controls to automatically start up the vehicle when automatic starting-up condition is satisfied.
One such example of a control apparatus of a hybrid vehicle is disclosed in published Japanese Application Laid-Open No. 9-71138.
The control apparatus for a hybrid vehicle indicated in this disclosure, includes a gearing means in a power transmission system from an internal combustion engine to a wheel, a power-generating/electrically-powered means, and an automatic start-up/stop control means. Incidentally, in the automatic start-up/stop control means, when a predetermined condition is satisfied at vehicle stop, then an internal combustion engine is stopped, and at re-start, an internal combustion engine is started up. Furthermore, at restart, the control apparatus has an engine rotational-speed restraining control means to control power-generating/electrically-powered means so as to restrain a rise of rotational speed of an internal combustion engine.
A control apparatus, when automatically stopping an engine of a hybrid vehicle, executes a stop processing that is stopping the supply of fuel to an engine.
However, an engine does not promptly stop even if the supply of fuel is stopped, and stops while running at idle by inertia. For this reason, while the engine idles, the fuel sticking in an inner wall of an intake port of the engine is drawn into a cylinder. Therefore, as an air-fuel ratio of fuel drawn into the cylinder while the engine idles becomes unsuitable, the fuel is drained in an incomplete combustion state or as an unburned combustible gas.
Accordingly, there is inconvenience and a problem in that effluent gas performance is deteriorated because the engine drains unburned combustible gas when the engine automatically stops. In addition, because the engine idles and does not stop quickly, the time period until an engine stops becomes long, and a sensation or feeling in the vehicle during stopping is undesirable. Furthermore, as a residual quantity of fuel in an intake port during running-idle decreases, there are inconveniences or waste in that fast explosion at a restart is delayed, and starting-up performance is deteriorated.
In order to obviate or minimize the above problem or inconvenience, the present invention provides a control apparatus for a hybrid vehicle having an engine and a electric motor disposed therein. The electric motor has both driving and recharging power-generating functions and is directly connected to the engine mounted on the hybrid vehicle. A control apparatus for the hybrid vehicle controls both driving and power-generating states of the motor based on a driving state of the hybrid vehicle and a driving state of the engine. The control apparatus automatically starts up and stops the engine according to an automatic start-up condition and an automatic stop condition, wherein when the engine automatically is stopping after the automatic stop condition is satisfied, the control means controls the motor so as to execute power-generating drive.
The control apparatus of the hybrid vehicle of this invention, when automatically stopping the engine after automatic stop condition is satisfied, controls the motor so as to execute a power-generating drive. Then, at automatic stop of the engine, by power-generating drive of the motor, the engine is given a load corresponding to an engine rotational speed. Accordingly, the engine cannot run to idle by inertia. Therefore, this arrangement can decrease the fuel sticking in an intake port of an engine that is drawn into a cylinder, and can retain the fuel in the intake port.